For an industrial oven used for heat-treatment and other like processes, in case an internal part of an oven is thermally insulated from an external environment and the oven is partitioned into various oven compartments thermally separated each other for the thermal control requirements, oven and partition walls are constructed in the form of the thermal insulation structures. Japanese Unexamined Patent Publication No. 2002-373586 describes an insulating structure installed to the exhaust cart of a continuous heat treating oven used to seal the hollow flat panel applied to a plasma display screen, the insulting structure being used to cover and thermally insulate the opening in the oven floor. That type of conventional oven insulating structure consists of hollow oven walls or partition walls into which thermal insulation is installed.
It is known that heating the thermal insulation material generally results in various substances forming or including the insulation material being gasified and discharged from the insulation into the local environment. It is imperative that impurities should be kept out of the internal environment of the oven which is used in the plasma display panel heating process. However, in case such a thermal insulation material is installed in the oven wall and partition wall, the internal oven environment is polluted. A means of overcoming this problem has been to run the oven through a break-in operation called “seasoning.” The heat generated during the break-in operation has the effect of previously releasing contaminants from the insulation material so that the internal oven environment will remain clean during the subsequent production heat treating operation.
There is, however, a problem associated with this break-in operation in that the insulation releases pollutants into the oven environment during seasoning, thus necessitating that the oven be cleaned before it can be used in the production heat treating process.
Moreover, due to the thermal insulation being installed within the walls having internally and externally facing surfaces, the externally facing surface is at a lower temperature than the internally facing surface during the seasoning operation when the thermal insulation is heated. This requires that the oven is seasoned for an extended length of time in order that the thermal insulation in proximity to the externally facing surface is heated to an extent which allows a sufficient amount of contaminants to be released. If sufficient seasoning time is not allowed, an adequate amount of contaminants will not be discharged from the thermal insulation. Measures have been taken to solve this problem by covering the externally facing surface of the walls with another insulation or by raising the temperature of the externally facing surface using a heater or blowing hot air thereon. These measures, however, increase costs and complicate operation.
Despite the application of the aforesaid measures, the internal environment of the oven must still be cleaned after the break-in operation. Running the oven for an extended break-in period, insulating the oven walls, and separately heating the oven walls are tasks which place an additional burden on oven operation in terms of time, operating cost, and labor.
Another method of rectifying the problem of insufficient contaminant release has been to prevent contaminants from discharging from the insulation into the oven by fabricating the wall members as gas-tight structures. This method, however, has the disadvantage of further increasing the cost of the oven.
It would therefore be advantageous to provide an oven apparatus capable of maintaining cleanliness of an internal oven environment which is devoid of contaminants released from the insulation during the seasoning operation, eliminating the need to clean the internal region of the oven after the seasoning operation is performed, and effectively removing contaminants released from the insulation during a significantly shortened seasoning time regardless of the temperature differential between the internal and external oven environments.